testdim {ade4}R Documentation

Function to perform a test of dimensionality

Description

This functions allow to test for the number of axes in multivariate analysis. The procedure is only implemented for principal component analysis on correlation matrix. The procedure is based on the computation of the RV coefficient.

Usage

testdim(dudi, ...)
## S3 method for class 'pca':
testdim(dudi, nrepet = 99, nbax = dudi$rank, alpha = 0.05, ...)

Arguments

dudi a duality diagram (an object of class dudi)
nrepet the number of repetitions for the permutation procedure
nbax the number of axes to be tested, by default all axes
alpha the significance level
... other arguments

Value

An object of the class krandtest. It contains also:

nb The estimated number of axes to keep
nb.cor The number of axes to keep estimated using a sequential Bonferroni procedure

Author(s)

Stephane Dray dray@biomserv.univ-lyon1.fr

References

Dray, S. (2007) On the number of principal components: A test of dimensionality based on measurements of similarity between matrices. Computational Statistics and Data Analysis, in press.

See Also

dudi.pca, RV.rtest

Examples

tab <- data.frame(matrix(rnorm(200),20,10))
pca1 <- dudi.pca(tab,scannf=FALSE)
test1 <- testdim(pca1)
test1
test1$nb
test1$nb.cor
data(doubs)
pca2 <- dudi.pca(doubs$mil,scannf=FALSE)
test2 <- testdim(pca2)
test2
test2$nb
test2$nb.cor

[Package ade4 version 1.4-11 Index]